Charles F. Delwiche
Ph.D. University of Wisconsin - Madison, 1990
Fax: (301) 314-9082
Research Interests: Plant Molecular Systematics
The algae are tremendously important organisms. They are critical to the maintenance
of atmospheric oxygen, form the foundation of aquatic food chains, and in the
late Ordovician gave rise to the land plant lineage. When eukaryotic diversity
is studied with molecular phylogenetic
methods, far more sequence divergence is found among algae and other protists
than in plants, animals, or fungi. This is consistent with the tremendous cytological
and biochemical diversity of protists, as well as with their relatively ancient
fossil records, but is frequently not reflected by structural diversity. Some
algal taxa (e.g., the green algal genus Chlorella) are junkyards housing
phylogenetically disparate taxa, while others -- typically those marked by an
unambiguous structural feature -- are natural groups by any measure. But even
in well defined algal taxa, considerable sequence divergence is often observed,
and the biological significance of this diversity at the molecular level is
not well understood. Recent advances in systematics, particularly the use of
molecular data analyzed with objective methods, have made it practical to reconstruct
the history or evolution with confidence. Information on how organisms are related
to each other can be used to infer how the features of those organisms evolved.
This comparative biological approach can be used to make generalizations about
groups of organisms that are not possible with reductive methods alone.
uses DNA sequencing, computer analysis, and structural and biochemical studies
to understand the phylogeny and evolution of algae, with particular emphasis on two problems; the early evolution
of plastids (i.e., chloroplasts), and the green algal origin of land plants.
There are two major projects currently underway in the lab. The first is a study
of the systematics and diversity of the Charophyta, the group of green algae
that gave rise to land plants. This study is funded through the NSF program
"Partnerships for Enhancing Expertise in Taxonomy (PEET)," and aims
to use state of the art techniques to understand the diversity, fundamental
biology, and develop appropriate classifications for this key group of algae.
The second project is focused on understanding the relationship between the
chloroplast and nuclear
genomes in dinoflagellates. Dinoflagellates are an environmentally and economically
important group of eukaryotes which include representatives both with and without
plastids. Furthermore, among those with plastids it is clear that plastids have
been acquired independently several times. By studying this history of plastid
acquisition we hope to gain insight into the factors that influence the origin
and evolution of plastids. This project has received funding from both the Alfred
P. Sloan Foundation and the National Science Foundation.
Delwiche, C. F., M. Kuhsel, and J. D. Palmer. 1995.
Phylogenetic analysis of tufA sequences indicates a
cyanobacterial origin of all plastids. Mol. Phylog. Evol.
Delwiche, C.F., and J. D. Palmer. 1996. Rampant horizontal
transfer and duplication of rubisco genes in eubacteria and
plastids. Mol. Biol. Evol. 13:873- 882.
Kohler, S., C.F. Delwiche, L.G. Tilney, P. Webster, R.J.M. Wilson, J.D. Palmer,
and D.S. Roos. 1997. A plastid of probable green algal origin in apicomplexan
plastids. Science 275:1485-1489.
Delwiche, C.F. 1999. Tracing the thread of plastid diversity through the tapestry
of life. The American Naturalist 154:S164-S177.
Tengs, T., O.J Dahlberg, K. Shalchian-Tabrizi, D. Klaveness, K. Rudi, C.F.
Delwiche and K.S. Jakobsen. 2000. Phylogenetic analyses indicate that the 19`hexanoyloxy-fucoxanthin-containing
dinoflagellates have tertiary plastids of haptophyte origin. Mol. Bio. Evol
Cimino, M.T., K.G. Karol, and C.F. Delwiche. 2000. An artifact in the SSU
rDNA sequence of Chaetosphaeridium globosum (Chlorophyta: Charophyceae).
Oldach, D.W., C.F. Delwiche, K.S. Jakobsen, T. Tengs, E.G. Brown, J.W. Kempton,
E.F. Schaefer, H.A. Bowers, H.B. Glasgow Jr., J.M. Burkholder, K.A. Steidinger,
and P.A. Rublee. 2000. Heteroduplex mobility assay guided sequence discovery:
elucidation of the small subunit (18S) rDNA sequences of Pfiesteria piscicida
and related dinoflagellates from complex algal culture and environmental sample
DNA pools. Proc. Natl. Acad. Sci USA: 97:4303-4308.
Karol, K.G., R.M. McCourt, M.T. Cimino, and C.F. Delwiche. 2001. The closest
living relatives of land plants. (submitted).
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